1. Field of the Invention
The present invention relates generally to preservatives for food and more specifically to a preservative that extends the shelf life of fresh cut fruit by reducing oxidation while preserving texture and flavor.
2. State of the Art
Fresh cut fruit will rapidly deteriorate once the fruit is exposed to air. This is particularly apparent when an apple is cut, and within minutes, the apple slices begin to brown. In addition, the flavor, texture, and crispness rapidly degrade and become significantly less appealing to be eaten. As such, it is often the case that fresh cut fruit is discarded because of its inability to maintain freshness over a relatively short period of time.
Some prior art methods of preserving fruit includes cooking, which changes the flavor, appearance and texture, freezing, which affects the texture and crispness, drying, which changes texture, flavor, crispness and appearance, refrigeration, which can help to preserve crispness and flavor but not appearance, the addition of films, such as wax films which are not desirable to be eaten, and the addition of chemical preservatives, which often significantly and detrimentally change the flavor of the food.
Natural substances such as salt, sugar, vinegar, alcohol, and diatomaceous earth are also used as traditional preservatives. Certain processes such as pickling, smoking and salting can also be used to preserve food but obviously have a significant effect on the flavor. Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, citric and ascorbic acids from lemon or other citrus juice can inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown. It is known in the art to use citric acid as a food preservative. Citric acid does help delay browning in fruits, but creates a sour taste in the fruit and also allows the fruit to lose its crispness. Sodium ascorbate has also been used to preserve fruit to prevent color degradation for a period of time, but produces a noticeable and unpleasing taste.
Ascorbic acid and its sodium, potassium, and calcium salts are commonly used as antioxidant food additives. These compounds are water-soluble and thus cannot protect fats from oxidation: For this purpose, the fat-soluble esters of ascorbic acid with long-chain fatty acids (ascorbyl palmitate or ascorbyl stearate) can be used as food antioxidants. Calcium ascorbate is a compound with the molecular formula CaCl2H14O12. It is the calcium salt of ascorbic acid, one of the mineral ascorbates. Among its many uses is to keep apples fresh, so they do not turn brown quickly.
U.S. Pat. No. 5,939,117 discloses a method of preserving fresh fruit with fresh fruit preservatives that claim to extend the shelf life of fresh fruit particularly fresh cut fruit. The method includes the steps of providing a solution of fruit preservative comprising water, calcium ions and ascorbate ions, wherein the calcium ions and ascorbate ions are present in a ion ratio of from about 1.5:1 to about 2.5:1, and applying the fruit preservative to the fruit.
U.S. Pat. No. 5,645,880 to McArdle, the entirety of which is incorporated by this reference, relates to a food preserving composition containing an acid and a protein-polysaccharide complex (PPC) composition. The PPC includes a water-soluble polysaccharide, such as Guar gum, a water-insoluble protein such as zein and an acid such as citric acid. The polysaccharide is in an amount of between about 90% to 99% of the total PPC composition. The protein is a prolamine such as zein and is in an amount of between about 10% and 1% of the PPC. The acid is in an amount of between about 0.25% to 5% by weight of the total PPC compositions. The acidulant may be added to the water of an aqueous organic solvent system prior to addition of the organic components although it may be added contemporaneously with other organic components. Zein is extracted from corn or maize. PPC compositions containing zein are used to form odorless, tasteless, clear, hard and nearly invisible films. The PPC composition is sold in the market under the trademark ICEIN. ICEIN is provided in a yellow to white free flowing powder and has a pH of 2.6 to 4.0 in a 1% solution I distilled water at 20 degrees Celsius. The PPC of U.S. Pat. No. 5,645,880 is used to preserve food, specifically seafood and dried fruits and is prepared by dissolving the PPC in an aqueous organic solvent containing alcohol and water in an amount of 100-300 grams of protein per liter of solution.
Among those familiar with the art have used various food preservatives, such as ascorbic acid and its sodium, potassium, and calcium salts to prevent oxidation. In addition, other food preservatives have included ingredients such as calcium, calcium ascorbate, citric acid, sodium acid pyrophosphate (SAPP), calcium chloride and sodium chloride. Each of these prior art preservatives, however, has a detrimental effect on the flavor of the fruit and often have limited effectiveness. Accordingly, it would be advantageous to provide a food preservative composition and method of using the composition to preserve fresh cut fruit that preserves the appearance, color and crispness for a period of days or weeks, and that has either no palatable affect or actually enhances the flavor of the fruit. The present invention provides a food preservative that includes, inter alia, naturally occurring nutrients in the fruit to preserve color, taste, texture and shelf life of fresh cut fruit.